Epidemiology of multidrug-resistant Gram-negative pathogens isolated from ventilator-associated pneumonia in ICU patients.

OBJECTIVES: Antibiotic resistance among Gram-negative pathogens isolated from ventilator-associated pneumonia (VAP) poses a grave threat in intensive care unit (ICU) patients. The aim of this study was to assess the prevalence of pathogens in ICU patients and their drug resistance profile. The prevalence of extended-spectrum ß-lactamases (ESBLs), AmpC ß-lactamases and metallo-ß-lactamases (MBLs) was also assessed. METHODS: Tracheal aspirates were collected aseptically from 87 ICU patients between May 2012 and January 2014. Cultured isolates were identified by standard microbiological techniques. Antimicrobial susceptibility testing was performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. ESBLs and AmpC ß-lactamases were detected both phenotypically and genotypically; MBLs were detected phenotypically. RESULTS: A total of 77 isolate were cultured. Gram-negative bacteria comprised 68 (88.3%) of the total isolates, among which 49 (72.1%) were multidrug-resistant (MDR). Gram-positive organisms comprised four (5.2%) of the total isolates and all four (100%) were MDR. Aspergillus fumigatus (6.4%) was the only fungal pathogen identified. CONCLUSIONS: Pseudomonas aeruginosa was the predominant pathogen associated with VAP. The rising trend of antibiotic resistance in Gram-negative organisms is alarming. Regular monitoring of the pattern of resistance in ICUs is critical in effective management of VAP patients.

Presence of metallo-beta-lactamases (MBL), extended-spectrum beta-lactamase (ESBL) & AmpC positive non-fermenting Gram-negative bacilli among Intensive Care Unit patients with special reference to molecular detection of blaCTX-M & blaAmpC genes.

BACKGROUND & OBJECTIVES: Non-fermenting Gram-negative bacilli (NFGNB) including Pseudomonas aeruginosa and Acinetobacter baumannii have been implicated in a variety of infections, particularly in the Intensive Care Units (ICUs). This study was aimed to overview the burden of multidrug-resistant NFGNB causing infections in ICU and also to assess the occurrence of extended-spectrum beta-lactamases (ESBLs), AmpC and metallo-beta-lactamases (MBLs) among these isolates. METHODS: Bacterial culture, identification and antibiotic susceptibility were carried out. ESBLs and AmpC were detected both phenotypically and genotypically. MBL was detected by modified Hodge and imipenem-ethylenediaminetetraacetic acid double-disc synergy test. RESULTS: NFGNB represented 45 (37%) of total 121 Gram negative isolates. Multidrug resistance was observed in 66.9 per cent and 72.5 per cent isolates of P. aeruginosa and A. baumannii, respectively. Detection by phenotypic methods showed presence of ESBL, AmpC and MBL in 21.4, 51.1 and 21.4 per cent isolates, respectively. When detected genotypically by polymerase chain reaction, ESBL and AmpC were detected in 21.4 and 41.4 per cent of NFGNB isolates, respectively. BlaCTX-M (21.4%) was the most prevalent gene responsible for ESBL production. INTERPRETATION & CONCLUSIONS: Most of the NFGNB isolated from ICU patients were multidrug-resistant and producers of ESBL, AmpC and MBL. A regular surveillance is required to detect ESBL, AmpC and MBL producers, especially in ICU patients.